1. Technical Field
The disclosure relates to a bearing device having good lubricant retention, a method of manufacturing the bearing device, and a bearing assembly having the bearing device.
2. Description of the Related Art
At present, bearings are widely used in spindle motors that are employed in various electronic devices, such as compact disc (CD) drives, digital video disc
(DVD) drives, hard disk drives, laser beam printers, floppy disk drives, and heat-dissipation fans. These spindle motors require bearings with a small size, a high rotational accuracy, and a long working lifetime.
A typical hydrodynamic bearing defines a bearing hole therein. A shaft is rotatably received in the bearing hole. Lubricant is often used between an inner circumferential surface of the bearing and an external circumferential surface of the shaft to reduce abrasion of the bearing and the shaft. There are three common types of hydrodynamic bearings; namely, a ball bearing, a fluid bearing, and a sleeve bearing. The structures of the ball bearing and the fluid bearing are complex, and so the cost of manufacturing the ball bearing and the fluid bearing is high. The structure of a common sleeve bearing is simple. However, when the sleeve bearing is manufactured using a molding process, the quality of the sleeve bearing is not very high. In particular, material interstices in the bearing are typically not small enough. As a result, friction between the lubricant and the bearing and friction between the lubricant and the shaft is large when the lubricant flows between the bearing and the shaft. Thus, an operating life of the bearing is not long.
Therefore it is desirable to provide a bearing device, a method of manufacturing the bearing device, and a bearing assembly to solve or at least mitigate the above-described problems.